1/ Global warming is just a theory and scientists
disagree about whether it is happening and whether it is
anything to do with human activity.

There is a very strong scientific agreement
in the scientific community that global warming is happening
and that it is a result of man's activities
in releasing carbon into the atmosphere that was locked
away for millions of years in fossil fuels.

The
evidence that the earth is warming is overwhelming

There will always be people who argue
the opposite to any idea and they are vital to avoid blind
adherence to what may turn out to be incorrect and to encourage
further investigation and refinement of ideas.

There comes a point however where an alternative
idea becomes something only considered by the occasional
maverick (and don't mavericks love the idea of being
a maverick?) and then just becomes something that isn't
considered seriously any more.

There is also the fact that many of the
articles that doubt global warming are sponsored by the
oil and related industries.

Many who doubt mans influence on global
warming by releasing carbon dioxide from fossil fuels are
driven by a dislike of taxes that are being raised by politicians
as a result. Arguments frequently start with not wanting
to pay tax and end up with deciding global warming is not
happening.

2/ The amount of carbon dioxide hasn't
risen enough and there is only a tiny amount of it anyway
- it can't possibly make any difference.

The amount
of atmospheric CO2 has gone from 0.0284% to 0.0382%
between 1832 and 2007. That's a 0.0099% increase in
the amount of CO2 in the atmosphere, or an approx
35% rise in the amount of CO2 compared to pre-industrial
levels.

That part of the atmosphere
known as the stratosphere is 50km thick (the atmosphere
goes beyond this to 690m, the edge of the "thermosphere"
and beyond, but this will do for now).

0.0382% of
this is a layer works out at 19.2m thick if all the CO2
was collected in a single layer (that's over 62 feet).

To try and put it in some kind of context, compare
this to the ozone layer. The ozone above our heads protects
us from ultra violet rays from the sun, without it life
on earth as we know it would be impossible (the immediate
effects would be appalling sunburn on overcast days).

If the ozone above our heads were collected
together in a continuous layer it would be about 3mm thick
(1/8th of an inch). Hard to believe? but true, by comparison
0.0382% at 19.2m is a huge thick duvet.

3/ Global
warming can't be true as the temperature in some places
is stable or falling.

Global warming models
differ as to the exact effects of where and to what extent
temperatures will change, but they all have one thing in
common - that the effect of global warming is not uniform.

Different parts of the world
react in different ways and one of them is that in the early
stages (where we are now) the temperature in some parts
of the world will actually fall or at least remain stable
which is what is being observed. Eventually as warming advances,
then most or all parts of the world will rise in temperature,
though again - not at a uniform rate.

4/ Global
warming is a good thing as I don't like the cold.

Well maybe
from a egocentric point of view it could be a good thing.
I live in the UK and many projections show that this will
increasingly become a more predictably warm, more attractive
and more pleasant place to live.

The areas that benefit however will be greatly
outweighed by the parts of the earth that become too hot
and dry to inhabit and by coastal towns and cities, including
some of the worlds greatest cities that may be flooded and
so have to be abandoned.

Hundreds of millions of people could suffer
from global warming, the winners will be a small proportion
by comparison.

5/ Volcanoes contribute most of the CO2
released into the atmosphere each year.

Scientists have calculated that volcanoes
emit between about 130-230 million tonnes (145-255 million
tons) of CO2 into the atmosphere every year
(Gerlach,
1999, 1992). This estimate includes both
subaerial and submarine volcanoes, about in equal amounts.

Emissions of CO2 by human
activities, including fossil fuel burning, cement production,
and gas flaring, amount to about 22 billion tonnes per
year (24 billion tons) [ (
Marland, et al., 1998) - The reference gives
the amount of released carbon (C), rather than CO2.].

Human activities release more than 150 times the amount
of CO2 emitted by volcanoes."

6/ The ozone
hole causes global warming.

The ozone hole
is the result of a loss of ozone in the upper levels of
the stratosphere which reduces the ability of the atmosphere
to absorb harmful ultra-violet light from the sun. This
is caused mainly by a group of chemicals called CFC's.

The hole in the ozone layer is a different
problem with different causes to global warming.

7/ If you
do the sums, it just doesn't add up, we don't produce
enough carbon dioxide to make any kind of difference.

The atmosphere consists
of a VAST amount of air, so even billions of tons of CO2
doesn't push the actual portion up that much.
Unfortunately though CO2 is incredibly effective
at being a greenhouse gas and so tiny amounts make big differences.
The figure in the air is around 0.04%. There's also
the fact that the oceans have been absorbing a lot of the
CO2 produced, so all of that extra produced is
not actually in the atmosphere.

The amount of carbon
dioxide in the air has increased in the last 150 years:

It has been doing so since
the industrial revolution and is currently outside of any
observed natural cycle:

1g of octane takes 3.5g of
oxygen to burn it fully. This is 1 molecule of octane and
12.5 molecules of oxygen. This produces just over 3g of
CO2 and 1.42g of water, respectively 8 and 9
molecules of each.

This is the counter-intuitive
part in that 1g of a tangible substance (petrol - octane
- an easily visible liquid) is producing more than 3g of
CO2 an invisible, odourless, colourless gas.
But the science all adds up correctly.

It means
that for a petrol (gasoline) car, the mass of CO2
emitted is 3 times the mass of petrol burnt!

Worth thinking about next
time you're standing by the pump as all the fuel goes
flooding into the tank, 50L of petrol weighs about 37kg,
this is the equivalent of 111kg of carbon dioxide being
released per tank full.

If we take a car that
emits a rather frugal 135g/km of CO2 emission,
we can work backwards from the figure of of CO2
and assuming perfect combustion of octane (mostly what petrol
is C8H18), this figure is equivalent
to 59 miles per gallon, which is actually pretty optimistic!

Water vapour in the atmosphere
is a result of temperature and dewpoint,
if I try to kick it out into the atmosphere but the physics
doesn't work it condenses out, carbon dioxide doesn't
work like that.

Water vapour may
add to the effects of global warming by adding to the earth's
heat retentive blanket in a positive feedback effect. More
carbon dioxide means warmer temperatures, means more water
vapour in the air, means warmer temperatures. Water vapour
alone is not the reason for global warming and certainly
not the starting point.

9/
Carbon dioxide released from
fizzy drinks released is a contributing factor to Global
Warming.

The good news is that
nearly all industrial carbon dioxide is reclaimed from processes
that release it in the first place rather than generate
it specifically for another use - so it is nearly always
recycled.

Of course that does
mean that it has been released, but it's cutting down
on the amount a little at least.

The carbon dioxide
that fizzes your drinks up today could have come from burning
fuel, yeast that were busy making beer or some chemical
process that releases it as a by-product.

10/
Exercise produces carbon dioxide, so if I don't do any
I'm helping the planet

We breathe out carbon
in carbon dioxide as a by-product of respiration, the more
we respire the more we produce.

This carbon came from the food we ate and
is a part of the natural carbon cycle whereby plants and
animals are balanced. It does not contribute to global warming
as it will be recycled when it is taken in by a plant for
photosynthesis.

The problem with carbon dioxide and global
warming comes from carbon released from fossil fuels where
the carbon has lain locked up in a carbon-sink for many
millions of years and is now released into the atmosphere.
If we didn't burn fossil fuels (or make cement) then
mankind would pretty much carbon-neutral - as we were before
the industrial revolution.